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!Environment Canada - Atmospheric Science and Technology License/Disclaimer, 
!                     version 3; Last Modified: May 7, 2008.
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***fonction schal - chaleur latente selon TT et SWPH
*

      function schal(tt, ti, swph) 6,4
*
#include "impnone.cdk"
*
      real tt, ti, schal
*
      logical swph
*
*author
*       N. Brunet (septembre 2000)
*
*revision
*
*object
*       to calculate the latent heat (J Kg-1) according
*       to temperature and swph
*
*arguments
*       tt - temperature in deg K
*       ti - temperature (K) at which we start calculating
*            latent heat of sublimation
*            if swph=false, ti is n/a
*            ti must be .LE. trpl
*
*note
*      if(not.swph) then schal is equal to folv
*      if(swph) at tt .le. ti, schal is equal to fols
*               at tt .ge. trpl, schal is folv
*               at tt between ti and trpl, schal is a linear
*               interpolation .
*
*implicites
#include "consphy.cdk"
*modules
      external inctphy
*
**
*---------------------------------------------------------------
*
      real lsti, lvt0
*
#include "dintern.cdk"
#include "fintern.cdk"
*
*--------------------------------------------------------------------
#include "initcph.cdk"
*
      if(swph)then
*
         if(tt.ge.trpl) then
            schal = folv(tt)
         end if
         if(tt.le.ti) then
            schal = fols(tt)
         end if
         if(tt.lt.trpl .and. tt.gt.ti .and. ti.ne.trpl)then
            lvt0 = chlc
            lsti = fols(ti)
            schal = (lsti-lvt0)*(tt-ti)/(ti-trpl)+lsti
            schal = max(min(schal,lsti), lvt0)
         end if
*
      else
*
         schal = folv(tt)
*
      end if
*
      return
      CONTAINS
#include "fintern90.cdk"
      end